Conventionally, it has been known to diagnose and analyze a vehicle behavior based on detection signals outputted from various sensors mounted on a vehicle. Such a technique is, for example, described in U.S. Pat. No. 5,754,965. Also, it has been known to store data outputted from various sensors before and after a vehicle receives an impact such as an impact of a collision as vehicle traveling data.
Further, it has been known, when a malfunction occurs in a sensor or an actuator, to store a diagnosis code according to the malfunction, and sensor outputs and control data according to a time axis as the operation data (freeze-frame data).
In a technique described above, the diagnosis code and the freeze-frame data are stored when the sensor or the actuator has a malfunction. For example, when a vehicle behavior that does not correspond to a driver's operation while the sensor and the actuator are in normal condition, the operation data at that time is not stored. Therefore, even if the driver feels uncomfortable due to the vehicle behavior that does not correspond to the driver's operation, the cause of the vehicle behavior is not analyzed based on the operation data of the vehicle.
For example, it is considered to set a determination condition to detect the vehicle behavior that does not correspond to the driver's operation, and to store the operation data when the vehicle behavior satisfies the determination condition. In such a case, it is possible to analyze the cause of the vehicle behavior that does not correspond to the driver's operation based on the operation data stored.
However, the cause of the uncomfortable feeling of the driver will be different depending on a road condition where the vehicle is or travels, such as whether the road is straight or curved, and whether the vehicle is on a road or in a parking. Therefore, if a threshold to define the determination condition is fixed, the following situation will occur.
For example, even if the vehicle has a behavior that causes uncomfortable feeling to the driver, when the behavior does not satisfy the determination condition, the behavior will not be stored as the operation data. Also, even if the vehicle has a behavior that does not cause uncomfortable feeling to the driver, when the behavior satisfies the determination condition, the behavior will be stored as the operation data. As a result, when the amount of storage of the operation data increases, the operation data regarding the vehicle behavior that causes the uncomfortable feeling to the driver will be overwritten due to the limitation of memory capacity.